Integrated Experimental Phase Equilibria and Thermodynamic Modelling Investigation of the FeO-Fe2O3-MgO and the FeO-Fe2O3-MgO-SiO2 Systems. Part I: Experimental Results in Air

Phase equilibria studies were undertaken on the FeO-Fe2O3-MgO-SiO2 and FeO-Fe2O3-MgO systems in air using an equilibration and quenching technique. Concentrations of Fe, Mg, Si in the coexisting phases were measured using electron probe X-ray microanalysis (EPMA) with a wavelength dispersive spectrometer (WDS) detector. The liquidus temperatures have been determined from 1 400 degrees C to 1 740 degrees C in primary phase fields of spinel, monoxide, olivine, pyroxene, tridymite, cristobalite and in two-liquids miscibility gap. Tielines between co-existing phases and the compositions of solid solutions have been determined. In the absence of a liquid phase which would facilitate mass transport, the subsolidus phase relations in the Fe2O3-MgO system were not studied directly. The measurements in the low-SiO2 area of pseudo-ternary "Fe2O3"-MgO-SiO2 system were used to derive phase equilibria of the "Fe2O3"-MgO pseudo-binary system with a special focus on the monoxide-spinel phase boundary. The present study is a part of the research program on the characterization of the MgO-containing refractory systems within the multicomponent Pb-Zn-Cu-Fe-Ca-Si-O-S-Al-Mg-Cr-Na-As-Sn-Sb-Bi-Ag-Au-Ni-Co system.